發(fā)布時間：2018-05-04 03:03

  本文選題：電脈沖處理 + 鋁銅合金　； 參考：《遼寧工業(yè)大學》2015年碩士論文

【摘要】：Al-Cu合金以其鑄態(tài)下優(yōu)良的耐熱性，及良好的機械性能與工藝性能在生產中廣泛應用。但其存在晶間耐蝕性較差的缺點，會使金屬的物理性能急劇下降，造成嚴重的安全隱患。因此，研究電脈沖作用下Al-Cu合金鑄造織構的轉變機理及其對耐蝕性的影響，揭示其作用本質，對于該類材料的使用以及提高材料的性能有著極為重要的意義。 本文以Al-5%Cu合金為研究對象，分別進行熔體電脈沖處理和液固兩相區(qū)電脈沖處理，觀察和分析合金的宏觀組織，使用X-射線衍射儀檢測其織構，研究電脈沖對其鑄態(tài)織構的影響，最后采用電化學工作站檢測其耐蝕性，通過鑄態(tài)織構的變化探討熔體電脈沖處理對耐蝕性的間接影響。 通過分析實驗現象，解釋了脈沖電磁場和溫度場對柱狀晶生長的影響機理。實驗結果表明，（1）熔體電脈沖處理時，隨著脈沖電壓的升高，宏觀組織內柱狀晶的出現與否具有周期性；隨著脈沖頻率的增大，柱狀晶區(qū)域逐漸減小，當頻率為15Hz時，柱狀晶消失，試樣組織中全部為細小的等軸晶。（2）液固兩相區(qū)電脈沖處理主要有兩方面影響：一方面會使表層晶粒平整；另一方面，電脈沖會縮小柱狀晶區(qū)，并降低內部等軸晶的尺度。（3）熔體電脈沖處理會對Al-5%Cu合金的鑄造織構產生重要影響，在溫度場與脈沖電磁場的耦合作用下，常溫金屬型冷卻條件下，，電脈沖對柱狀晶生長的抑制效果顯著，而500℃條件下，其抑制效果消失。整體來看，隨著溫度場的減弱，織構的總體積分數逐漸減小。（4）電脈沖對Al-5%Cu合金耐蝕性的影響顯著，通過改善Cu原子的偏析，顯著改善合金的耐蝕性；隨著溫度場作用的減弱，電脈沖對合金耐蝕性的改善效果逐漸增強。
[Abstract]:Al-Cu alloy is widely used in production for its excellent heat resistance and good mechanical and technological properties in its cast state. However, the poor corrosion resistance of the alloys will lead to a sharp decline in the physical properties of metals and cause serious safety problems. Therefore, the study of the transformation mechanism of the Al-Cu alloy casting texture and its pair is studied. The influence of corrosion resistance reveals the nature of its action, which is of great importance for the use of such materials and the improvement of the properties of materials.
In this paper, the Al-5%Cu alloy was taken as the research object, the melt electric pulse treatment and the liquid solid two phase region electric pulse processing respectively, the macroscopic microstructure of the alloy was observed and analyzed, the texture of the alloy was detected by the X- ray diffractometer, and the influence of the electric pulse on its as cast texture was studied. Finally, the corrosion resistance of the alloy was detected by the electrochemical workstation. The indirect effect of melt electric pulse treatment on corrosion resistance was discussed.
By analyzing the experimental phenomena, the influence mechanism of pulsed electromagnetic field and temperature field on columnar crystal growth is explained. The experimental results show that (1) when the melt electric pulse is treated, with the increase of the pulse voltage, the appearance of the columnar crystal in the macrostructure is periodic. With the increase of the pulse frequency, the columnar crystal gradually decreases, when the frequency is 15Hz When the columnar crystal disappears, the specimen microstructure is all fine equiaxed grains. (2) the electrical pulse treatment in the liquid solid two phase region has two main effects: on one hand it will make the surface grain smooth; on the other hand, the electric pulse will narrow the columnar crystal region and reduce the scale of the internal equiaxed grains. (3) the melt electrical pulse treatment will produce the casting texture of Al-5%Cu alloy. Under the interaction of temperature field and pulsed electromagnetic field, under the condition of metal cooling at normal temperature, the inhibition effect of electric pulse on columnar crystal growth is remarkable, and the inhibition effect is disappearing at 500. As a whole, the overall integral number of the texture decreases with the decrease of temperature field. (4) the corrosion resistance of Al-5%Cu alloy by electric pulse The corrosion resistance of the alloy was greatly improved by improving the segregation of Cu atoms. With the weakening of the temperature field, the effect of electric pulse on the corrosion resistance of the alloy was gradually improved.

【學位授予單位】：遼寧工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TG290

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